1. Field of the Invention
This invention relates to well tools and more particularly to devices for releasably anchoring well tools in well flow conduits.
2. Description of the Prior Art
Locking devices for anchoring well tools in flow conduits of wells have been used for many years. Many such locking devices carry keys or locking dogs which engage in specially prepared lock recesses or configurations formed in special landing receptacles or nipples made up in the tubing of these wells. Normally, a specially prepared bore wall, one made smooth by honing, is formed adjacent the lock recesses and generally immediately therebelow so that when the keys or dogs of the locking device are engaged in the locking recesses of the landing receptacle, resilient seals carried on the locking device will be sealingly engaged with the smooth bore wall immediately therebelow.
The following U.S. Patents disclose locking devices and/or landing receptacles therefor.
U.S. Pat. Nos. 2,673,614, 3,419,075, 4,043,392, 3,208,531, 3,472,070.
U.S. Pat. No. 2,673,614, issued to I. A. Miller on Mar. 30, 1954, discloses a locking device having locating keys which are engageable in a specially prepared landing receptacle which is connectable into the tubing string to form a part thereof. These locating keys are formed with a pair of external bosses, the lower end of the upper boss being provided with an abrupt downwardly facing locating shoulder which is engageable with a corresponding abrupt upwardly facing shoulder formed in the landing receptacle. This locking device is lowered into the well until the abrupt shoulders on the keys and the landing receptacle engage to arrest the downward movement of the device in the well conduit. The device is thereupon lifted to expand locking dogs on the device into locking engagement with a locking recess formed in the landing receptacle.
U.S. Pat. No. 3,208,531 issued to Jack W. Tamplen on Sept. 28, 1965. This patent discloses a locking device having keys configured similarly to those of the locking device of U.S. Pat. No. 2,673,614 just mentioned in that the key is configured with two external bosses, the upper one of which is provided at its lower end with an abrupt downwardly facing locating shoulder. This locating shoulder is engageable with a corresponding abrupt upwardly facing shoulder in a specially prepared landing receptacle to limit downward movement of the locking device in the flow conduit. In this particular device, however, a special running tool is utilized to lower the locking device completely through the landing receptacle and then to lift it upwardly therethrough, and this upward movement prepares the device for setting upon being lowered into the nipple the second time. In this case, the locating keys also serve as the locking keys.
U.S. Pat. No. 3,419,075 issued to Norman F. Brown on Dec. 31, 1968. This patent discloses a mechanism having locating keys configured much like the locating keys mentioned hereinabove but also having means thereon for retracting the keys to disengage their abrupt locating shoulder from a corresponding shoulder in the landing receptacle of the well tubing.
U.S. Pat. No. 4,043,392 issued to Imre I. Gazda on Aug. 23, 1977. This patent discloses a well tool having locating keys provided with several external bosses, and these keys are provided with two oppositely facing shoulders. The keys on this device serve the purpose of sliding a sleeve valve from its upper position to its lower position when the device is installed in the landing nipple connected immediately above the sliding sleeve valve. When the device is removed from the landing nipple, the keys will slide the sliding sleeve valve back to its upper position. In this particular case, the sliding sleeve valve controls admission of control fluid from a control line into the receptacle assembly so that control line pressure conducted from the surface can be used to control a surface controlled subsurface safety valve for protection of the well. The keys of this device are retracted in a manner similar to that taught in U.S. Pat. No. 3,419,075 mentioned hereinabove.
U.S. Pat. No. 3,472,070 issued to David V. Chenoweth on Oct. 14, 1969. This patent discloses a landing receptacle for well conduit, this receptacle being provided with an annular recess providing a pair of oppositely facing abrupt shoulders. A locking device is also disclosed having one set of keys pivotally mounted on the device so that one end of the keys projects outwardly beyond the periphery thereof and engages the recess to limit the movement of the locking device in one direction in the landing receptacle and a second set of keys pivotally mounted to the device and one end thereof which likewise projects outwardly beyond the periphery of the device and engages in the recess to limit movement of the device in the other direction in the landing receptacle. While the upper ends of the keys project outwardly, their inner ends project inwardly. A prong is moved into the bore of the device to engage the ends of the keys which project inwardly and thus pivot the keys to recess disengaging position. To limit movement of the device in the receptacle in either direction, the keys engage the abrupt shoulder either at the upper end or at the lower end of the recess.
None of the prior art devices with which applicant is familiar teaches a locking device for releasably anchoring a well tool in a well conduit, said locking device having locking keys with a pair of oppositely facing abrupt lock shoulders thereon engageable with a pair of corresponding oppositely facing abrupt lock shoulders in a landing receptacle of the well conduit, said locking device having a biasing member for biasing each locking key outwardly and having a mechanism including a retractor sleeve for retracting the locking keys to releasing position in response to upward movement of the retractor sleeve relative to said keys, there being coengageable camming surfaces on the keys and the retractor sleeve.